55 lines
1.5 KiB
Mathematica
55 lines
1.5 KiB
Mathematica
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:- module day4.
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:- interface.
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:- import_module basics.
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:- import_module list.
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:- import_module univ.
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:- pred run(part::in, list(string)::in, univ::out) is cc_multi.
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:- implementation.
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:- import_module int.
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:- import_module char.
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:- import_module string.
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:- type ranges ---> r(int, int, int, int).
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:- pred number(int::out, chars::in, chars::out) is semidet.
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number(N) --> digits(S), {to_int(from_char_list(S), N)}.
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:- pred digits(chars::out, chars::in, chars::out) is semidet.
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digits([C | Cs]) -->
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[C], {is_digit(C)},
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(if digits(Cs2) then {Cs = Cs2} else {Cs = []}).
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:- pred int_pair(int::out, int::out, chars::in, chars::out) is semidet.
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int_pair(A, B) --> number(A), ['-'], number(B).
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:- pred ranges(ranges::out, chars::in, chars::out) is semidet.
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ranges(r(A, B, C, D)) --> int_pair(A, B), [','], int_pair(C, D).
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:- pred ranges(string::in, ranges::out) is det.
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ranges(Str, R) :-
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if ranges(R2, to_char_list(Str), []) then R = R2
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else die("invalid line: ""%s""", [s(Str)]).
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:- pred all_overlap(ranges::in) is semidet.
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all_overlap(r(A, B, C, D)) :- C >= A, D =< B ; D >= B, C =< A.
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:- pred any_overlap(ranges::in) is semidet.
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any_overlap(r(A, B, C, D)) :- A =< C, B >= C ; C =< A, D >= A.
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:- pred go(pred(ranges)::(pred(in) is semidet),
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list(string)::in, int::out) is det.
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go(P, Lines, Out) :-
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map(ranges, Lines, Ranges),
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filter(P, Ranges, Overlaps),
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length(Overlaps, Out).
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:- pragma no_determinism_warning(run/3).
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run(one, Lines, univ(Out)) :- go(all_overlap, Lines, Out).
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run(two, Lines, univ(Out)) :- go(any_overlap, Lines, Out).
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